1. Field of the Invention
This invention relates to an image forming apparatus that uses an ink or dye ribbon, including electroresistive ribbon types, and one or more forms of energy to cause the transfer of a selected portion of ink or dye or the like to a substrate to prepare (i.e., precoat) that substrate for subsequent image formation, to overcoat an image already formed, to form an image directly, or to form an intermediate image for subsequent transfer to form a permanent image. More precisely, this invention relates to a series of combination ribbon types that include more than a single kind of ink or dye panel, especially panels of different sizes, types and colors and/or black, white or transparent or the like. In a second aspect, the invention relates to apparatus that permits selection of desired panels within a particular installed ribbon for use, while also taking account of which panels or parts of panels have already been used, even if a ribbon has been removed and reinstalled or is installed into a different printer that also embodies the features of the invention.
2. Background Information
U.S. Pat. No. 4,503,095 issued Mar. 5, 1985 to Seto et al. describes a heat-sensitive color transfer medium comprising a foundation on a front side of which, in repeating units, is disposed a multiplicity of equal-sized areas coated with heat-sensitive inks of differing colors. One embodiment of the Seto et al. medium includes within the repeating unit coated areas having the primary colors yellow, magenta and cyan, and a second embodiment also includes within the repeating unit an area of black. The transfer of ink is caused by electrical pulse signals for each color that have been defined to reproduce the desired composite image, which signals are transmitted to a thermal head. Superposition of the yellow, magenta and cyan colors upon a substrate of the same size as the coated areas permits the transfer either of multicolor or black images. When using a medium that includes a black area, a black image can be formed simply by transfer of the black ink.
Seto et al. describes alternative embodiments of the invention in which the medium may be of a single line width, to be used with a serial printer equipped with appropriate thermal heads which encompass that same width, whereby the medium and thermal head must both be moved across the substrate in order to form the full image of a particular color; and a second embodiment in which the medium has the same dimension as the substrate and thus only the thermal head must be moved to form that full image. However, in either such embodiment the Seto et al. invention is specifically limited to devices in which the coated areas of the ink transfer medium all have a longitudinal dimension which matches the corresponding dimension of the substrate to which the image is to be transferred.
U.S. Pat. No. 4,616,236 issued Oct. 7, 1986 to Watanabe et al. describes a color ribbon and apparatus by which, based upon the size of the substrate to which a transfer is to be made, if an image to be tranferred encompasses compasses less than one half of a color panel, only onehalf of the panel is used in a first color transfer, and the unused portion of the color panel can be used later for a second color transfer from that same panel. Since prior art devices ordinarily placed the image to be transferred in a position corresponding to the center of the color panel, the unused portions of the panel in such a device will consist of two separate portions lying on either side of the used portion and will thus not be readily amenable for use. Therefore, the Watanabe et al. '236 device makes provision for aligning the first image of less than one-half panel size with the forward or leading half of the panel, whereby the unused portion of that panel, i.e., the rear or trailing half, constitutes a single portion of like size that by means of reversible motors can be positioned for subsequent use. Operation of the Watanabe et al. '236 device presumes that at the outset the color transfer ribbon has not been used, so that when operating in the mode in which each color panel is to be used twice, a counting device is used to establish an even or odd copy count and thereby to provide for use of the leading or trailing halves of each color panel, respectively. Bar codes disposed along an edge of the transfer ribbon are read by a bar code sensor to control the ribbon drive motors and thus to position the ribbon panels as required. A limitation of the device, however, is the inability to distinguish used from unused panel portions on other than a one-half basis, i.e., to identify and then position for use various unused panel portions in general, as to ribbons that are both already and newly installed.
U. S. Pat. No. 5,104,247 issued Apr. 14, 1992 to Ohshima describes ribbons having ink panels of a length that may greatly exceed the size of the paper onto which an image is to be transferred. It is also presumed that in the prior art, panels of different colors will be individually marked by bar codes so as to identify the color of each. It would thus be the practice to wind such a ribbon (as mounted in a ribbon cassette) through the printer until a panel of a desired color was found, thereby passing over panels of other colors that would not have been used. Also, if the amount of printing (i.e., length of required color panel) was greater than the length of a particular color panel in use, to complete that printing it would be necessary first to interrupt that printing and then to wind through the ribbon again until another panel of that same desired color was found, which would again pass over panels of other colors. The use of longer color panels on the ribbon to accommodate more printing of a particular color at a time was not viewed as a complete solution to the above problem for the reason that when printing on smaller documents (e.g., post cards), substantial portions of such longer ribbon panels would similarly need to be passed over to get to a next-desired color panel. Inclusion of shorter color panels for such purposes would similarly be impractical, and could result in error because of the need to identify both the color and size of a panel.
The Ohshima '247 patent thus describes a method and apparatus for virtually dividing long and continuous panels of each particular color, as detected by detection means from bar codes interposed in between such color panels, into a preselected number of areas and carrying out the desired printing in units of such divided areas. The ribbon has a width appropriate for single line printing, hence the length of each such area is preferably slightly longer than one line length, i.e., than the width of the document to which the image is to be transferred. Discrimination means formed in the cassette are first employed to determine whether or not a particular ribbon is intended to be so divided, based upon whether or not the user has broken off a lug thereon prior to installation in the printer. If divisional use is indicated, the user must also input to the printer the number of fractional areas (e.g., areas A, B, and C) into which the total length of an inked region is to be divided. Upon fully traversing a ribbon using One area (e.g., A) for a particular color, a "use count" N is initiated that will subsequently cause positioning of the ribbon so that an as-yet unused area (e.g., B) becomes aligned with the print head for use. Additional discrimination means are employed to indicate to the printer that a particular ribbon is, e.g., monochromatic.
U.S. Pat. No. 4,704,615 issued Nov. 3, 1987 to Tanaka encompasses the thermal transfer of either a white or transparent ink layer onto a substrate prior to the transfer thereto of primary color inks to form the desired sired multicolor image. The "white" signal is generated by passing the yellow, magenta and cyan signals through an OR circuit so that white or transparent ink is first transferred to every location at which any or all of the yellow, magenta or cyan inks are to be transferred so as to smooth the surface to accept those latter inks. As in the Seto et al. '095 device, the color panels are of the same size as the substrate and are arranged on the transfer medium in the usual order of use; e.g., as white, yellow, magenta and cyan.
U. S. Pat. No. 4,977,058 issued Dec. 11, 1990 to Miyagawa et al. treats the speed at which thermal printing can be carried out, since thermal transfer (i.e., the heating and cooling of the elements of a thermal head) occurs at a much slower rate than, e.g., electric current or light, and also the fact that full color printing generally requires three successive operations to encompass the yellow, magenta and cyan colors, which introduces the problem of accurate image registration as well as the expenditure of considerable amounts of printing time. The use of image transfer materials that are sensitive to light only has been described, e.g., combinations of chromogenic materials and an encapsulated radiation curable composition, or a developer and a photosensitive microencapsulated material, but the use of such materials is limited by the high levels of light intensity required to effect exposure, the instability of the resultant image, the need to apply pressure in the microencapsulated case, and the poor storage stability of such materials. In consequence, the Miyagawa et al. '058 patent describes a layered transfer recording medium in several embodiments that is acted upon by both light and heat so as to bring about changes in medium parameters such as a softening, melting or glass transition temperature or the viscosity in the transfer layer. Image transfer requires special apparatus in the printer, i.e., a separation transfer unit and a transfer image formation unit.
In the general context of positioning a ribbon for use, U. S. Pat. No. 4,558,329 issued Dec. 10, 1985 to Honda describes the use of an ink region or color panel indicator mark for each color panel, specifically in marker blocks formed on the base material of the ribbon. In the prior art, one set of marks on one side of the ribbon was used to identify the start of each color group, e.g., a grouping of yellow, magenta, cyan and black panels, and another set of marks on the opposite side of the ribbon marked each individual panel within such panel groups. Such marks were formed in a separate manufacturing process and entailed the deposition, e.g., of carbon film that was detectable by its shielding of an incident infrared diode from a photodetector. In the Honda '329 patent, a material (e.g., an inorganic salt) that will provide the desired absorption of infrared light but is heat stable and thus will not be transferred from the ribbon during the thermal printing process is included in the ink or dye formulation, and such marks are formed in the same ribbon manufacturing process as that which deposits the ink or dye onto the ribbon.
U. S. Pat. No. 4,893,951 issued Jan. 16, 1990 to Iwatani et al. describes means for avoiding the repetitive use of marker blocks for each color panel and the consequent use of substantial amounts of ribbon material therefor, specifically by marking only each sequence of color panels (conventionally, yellow, magenta, cyan and perhaps black in equal-sized panels) instead of marking the individual color panels. The amount of ribbon feed following identification of a new panel sequence is then monitored by counting pulses generated from the ribbon supply or take-up reel in order to permit calculation, after printing in one color, of the start of the next panel, to which the ribbon can then be moved. Alternatively, the Iwatani et al. device also establishes known distances between panel sequences and similarly positions the ribbon based upon calculations from an initially located panel sequence. To do so, the known distance between panel sequences is correlated with the pulse count from the pulse generator to obtain a rotary pulse count-to-linear distance relationship that is used to locate each panel sequence. Printing is carried out in cycles corresponding to such panel sequences and providing full color image printing for one sheet of substrate--i.e., so as to make one full color copy of the desired image.
A source of inaccuracy in the aforesaid procedure is that since the amount of ribbon on the take-up reel will continually increase, so as to yield an increasing cross-sectional diameter, the actual rotary pulse count-to-linear distance relationship is constantly varying, which means that (1) it must be redetermined for each panel sequence; and (2) even as to one panel sequence, the value so determined at best represents an average of such relationship over the length of the particular panel sequence on which the relationship is being measured. What is thus needed in this context is a means for determining color panel positioning that relies upon the linear relationships of the color ribbon itself, and not upon indirect and inaccurate values determined from reel rotational data.
In the multipanel devices previously set forth, each of the panels of the respective transfer media has been of the same size. U.S. Pat. No. 4,638,330 issued Jan. 20, 1987 to Watanabe describes an image forming apparatus and transfer medium in which at least one panel or region is larger than the others. Thus, the color panels may be of letter size, on the assumption that color images are more often placed on letter size than legal size paper, whereas the black panel is of legal size on the assumption that text is more often placed on legal size paper, or other choices can also be established. In any case, ink transfer is commenced at or near a leading edge of both each color (or black) panel and the particular size paper being used, and actual ink transfer is controlled by color or black signals being sent to the thermal head in the usual manner. As in the multipanel ribbons previously noted, however, it remains that the panel sizes are established so as to match one or the other size of paper onto which an image is to be transferred.
In the context of impact printers such as an ordinary typewriter, and particularly with respect to various single- or multistrike film or fabric ribbons, or ribbons having black and colored inks distributed in longitudinally separate sections thereon, including a black section and additional sections, e.g., of red, yellow, blue or green ink, U.S. Pat. No. 4,797,016 issued Jan. 10, 1989 to Lahr describes a method of encoding such ribbons with machine-readable information concerning the ribbon type (film or fabric, single- or multistrike, and what ink colors are available on the ribbon) as well as the particular longitudinal position along the ribbon that at the moment is adjacent the printing mechanism, together with information concerning the length of ribbon that remains unused. The ribbon type and remaining ribbon information is distributed along the ribbon so that it can be read by an operator at any time in the course of using the ribbon, thereby avoiding misapplication of an inappropriate ribbon type or initiation of a printing job for which insufficient ribbon is available, and the ink type information is also immediately available so that an operator can confirm whether the ribbon provides the desired color of ink. The information of the various types is printed onto the back (non-printing) side of the ribbon in standard bar code at the time of ribbon manufacture, for which ordinary, magnetic, or fluorescent ink may be used in conformity with the type of code reader to be placed on the printer.
(A method of thermally printing such bar codes onto lo a perforated record medium so as to provide bar code sticker labels is disclosed in U.S. Pat. No. 3,726,212 issued Apr. 10, 1973 to Combs. However, unless such printing is done in an area on the ribbon that is not further accessible to a thermal print head, to print such codes thermally onto a ribbon that itself acts as an ink or dye source, and thus is to be subjected to a thermal print head, introduces the possibility of remelting those bar codes and rendering them unreadable in the course of using the ribbon.)
The ribbon type information just discussed can also be placed at the leader end of the ribbon to be read by the printer and stored in memory at the time of ribbon installation, so that any discrepancy between such stored information (which may have been used to make adjustments to the printer) and that being read along the length of the ribbon will indicate that a ribbon has been replaced (so the printer may no longer be appropriately adjusted). A disadvantage of the Lahr method is that the parallel lines or bars which together make up the bar code are oriented transversely to the longitudinal dimension of the ribbon, hence the bars themselves are distributed longitudinally along the ribbon, so that an entire bar code group (e.g., fifteen positions) extends some distance (e.g., 3 inches) along the ribbon, and the ribbon must be moved at least that distance in order to fully read the code. (The orientation of the bar code groups appears not to have been considered in the Watanabe et al. '236 patent noted above.)
The encoding of ribbon type information, including a ribbon having a single long panel, e.g., of black, is further described in U.S. Pat. No. 4,910,533 issued Mar. 20, 1990 to Sasaki et al. Such information is provided to the printer at the time the ribbon is loaded. The ribbon type information is encoded onto either or both of two ribbon core members which act as supply and take-up rolls for the ribbon, the means of such encoding being, e.g., a layer of paint of a particular color, a knurled surface area, splined grooves, or some combination thereof. Optical sensors (i.e., a combined light emitter and detector) on the printer interpret the code so provided, whereupon the printer selects a mode of operation that will ensure proper use of the ribbon type so identified. It is also noted, however, that the ribbon type code may instead be placed on the side marginal area of the ribbon itself.
A use of position coding in the context of multi-color thermal printing similar to that of the Lahr '016 patent is found in U.S. Pat. No. 5,073,053 issued Dec. 7, 1991 to Kashiwagi. However, in this case the position discrimination marks employed are not bar codes but single lines of two different lengths oriented along one edge of the ribbon within each of the equal-sized color panels of the ribbon. Two optical sensors are positioned over the ribbon path at that same edge, and in a straight line along the long ribbon dimension, such that in passing the position discrimination marks under those sensors as the ribbon is moved forward, when a mark is read by both sensors in succession, depending upon the length of the mark the two optical sensors will or will not detect changes (high to low, low to high, or high to high) in the light reflected from those position discrimination marks, thereby identifying the particular color panel as yellow, magenta, or cyan, respectively. Disadvantages of this procedure lie in the fact that the ribbon must be traversed the full distance between the optical sensors in order to identify the panel, and placement of the position discrimination marks within the ink panel appears to render the portion so marked unuseable.
To indicate the prior art in general, FIG. 1A is a plan view of a ribbon 10a having disposed on one side thereof a multiplicity of panels to which heat can be applied to cause the transfer of ink or dye therefrom to a substrate to form an image. Ribbon 10a includes ink or dye panels of three different color types: a first color panel 12a of a first color (e.g., yellow); a second color panel 14a of a second color (e.g., magenta); and a third color panel 16a of a third color (e.g., cyan). Each of color panels 12a-16a has a dimension in the longitudinal direction of ribbon 10a equal to the length or width of a common paper size, e.g., 11 inches, and has a transverse dimension equal to the width or length of that paper size, e.g., 81/2 inches. Of course, the color panels of ribbon 10a can also be formed in other paper sizes such as A4 (210 mm.times.297 mm), etc. In use, ribbon 10a is attached at each end thereof to rolls (not shown) which serve to move ribbon 10a in the direction of arrow 18a such that selected ones of color panels 12a 16a, in a predetermined sequence, can be placed adjacent to a printing head (not shown) so as to permit the transfer from each selected color panel of ink or dye of the color that characterizes that color panel. It is possible to obtain a black image from superposition of the yellow, magenta and cyan colors, but the quality of such an image is low, and of course the need to conduct three image transfers is time consuming.
Ribbon 10a also includes a border 20a (the width of which, and of the analogous borders 20b and 20c in FIGS. 1b and 1c are exaggerated for purposes of clarity) along one longitudinal side thereof within which, near the leading (as shown by arrow 18a) edge of each color panel, are placed indicating marks which serve to establish the start of each color panel. External sensors (not shown) are used to detect a double marker 22a disposed near the leading edge of first color panel 12a to indicate the start of panel 12a (yellow); a first single marker 24a disposed near the leading edge of second color panel 14a to indicate the start of panel 14a (magenta); and finally a second single marker 26a disposed near the leading edge of third color panel 16a to indicate the start of panel 16a (cyan). An example of this type of apparatus may be seen in the Tektronix Phaser II thermal transfer printer.
FIG. 1B shows a ribbon structure analogous to that of FIG. 1A but which also includes a black panel to allow production of a higher quality black image. Specifically, ribbon 10b has disposed thereon, in a manner similar to ribbon 10a, a first color (yellow) panel 12b; a second color (magenta) panel 14b; a third color (cyan) panel 16b; and a fourth color (black) panel 17b. Arrow 18b, border 20b, double marker 22b, first single marker 24b and second single marker 26b are disposed as and serve analogous functions to the corresponding elements of FIG. 1A. Ribbon 10b also includes a third single marker 28b disposed near the leading edge of and serving to identify the start of black panel 17b.
FIG. 1C shows a ribbon 10c similar to ribbon 10a shown in FIG. 1A except that the three color panels on ribbon 10c are not contiguous. (A similar structure that included a black panel as in FIG. 1B could of course be drawn as well.) That is, the analogous yellow panel 12c, magenta panel 14c, and cyan panel 16c are separated by a first space 30c between yellow panel 12c and magenta panel 14c; a second space 32c between magenta panel 14c and cyan panel 16c; and a third space 34c between cyan panel 16c and yellow panel 12c. FIG. 1C includes an arrow 18c to show the direction of ribbon flow, but ribbon 10c may or may not include a border 20c, as shown by the dashed lines of FIG. 1C. (Typically, ribbon 10c would not include such a border, since it is the purpose of spaces 30c-34c to eliminate the need therefor, thereby permitting each color panel to extend the full width of the ribbon as shown.) Also, ribbon 10c does not include the same double and single markers as do ribbons 10a or 10b since it is the specific purpose of spaces 30c-34c to provide different locations for indicating not only the leading edges of the various panels but also their colors. Instead, ribbon 10c includes a first code mark 36c in first space 30c to indicate the start of yellow panel 12c, including the color thereof; a second code mark 38c in second space 32c to indicate the start of magenta panel 14c, as well as the color thereof; and a third code mark 40c in third space 34c to indicate the start of and color of cyan panel 16c. Code marks 36c 40c may consist of bar code as in the Watanabe et al. '236 patent, an aperture as in the Iwatani et al. '951 patent, or of infrared-absorbing or reflective material as in the Honda '329 patent.
With respect to the apparatus that will employ ribbons such as ribbons 10a-10c, it is known in the art to incorporate within the apparatus certain mechanical, magnetic, electronic or optical sensors that determine what type of ribbon roll has been installed, including the type of ribbon and the size, colors, repeat sequences and numbers of different panel types thereon, as well as such operating parameters as heating requirements and optimum print head pressures. The particular sensor type used may respond, e.g., to the diameter of the ribbon roll markings on the ribbon cassette, ribbon rolls or in the ribbon fields, bar codes on the ribbon shaft, and the like. Such information may be included or repeated by markings that identify each color panel. Upon identification by such means of the type of roll that has been installed, and within a range of types (typically about six types) that a particular printer can accommodate and for which it has been pre-programmed, a printer control board within the printer employs information previously stored in ROM or installed as "firmware" and corresponding to the roll type so identified to control the use of the particular ribbon. However, except by the limited means previously noted from the Watanabe et al. '236 patent and pertaining to panel halves only, or similarly from the Ohshima '247 patent, what has not been provided is any means for determining and recording, in the course of using a particular ribbon, which panels or portions thereof have been used.
A common feature of the aforesaid prior art, commencing with Seto et al. ('095), is that the various color panels are specifically sized to correspond to the sizes of the paper onto which an image is to be transferred. Watanabe et al. ('236) describes an image forming apparatus and transfer medium in which at least one panel or region is larger than the others, but still the sizes indicated are such as to conform, e.g., to A4 and A5 paper, in which one paper size is exactly twice that of the other, or nearly so. Secondly, color selection in the prior art often rests either entirely or in part upon the use of a transfer medium in which the specific order of colors in the various color panels is fixed and known, so that at least one of the color panels (typically, two or three out of a set of three or four) can only be selected on the basis of that order. Also, except for Tanaka ('615), the application of which is limited to the thermal transfer of a white or transparent ink layer onto a substrate, the art has not provided means or apparatus for economically printing other than standard black and white or multicolor images without excess wastage of ribbon. Many printing applications require the ability, e.g., to carry out highlighting, i.e., the application of additional single color overprinting for emphasis on an existing color or black and white print, and it is not economical to use ribbons designed for full color printing for that more limited purpose.
Perhaps the major consequence of these limitations in the prior art, however, is that printing tasks exist in a very wide variety--some black and white, some two-color, some three-color but in which one of the colors may be used only slightly, etc. For many of these tasks the limited variety of ribbons available, together with the inability of existing apparatus to employ other ribbon types even if they were available, causes an inordinate waste of ribbon. Such waste arises from the inability to adjust the size of a color panel to the amount of printing that a task is expected to require, to obtain and maintain any record of what portions of any particular ribbon or ribbon panel have been used, or indeed to scan any such record even if it did exist and thus to permit rotation of the ribbon roll so that unused portions even within a single panel could be moved to the location of the print head for use. What is needed and would be useful, therefore, is a type of transfer medium in which the relative sizes and order of the respective color panels, and indeed of a wide variety of different panel types, can be pre-established at will, and also an image forming apparatus that is capable of accepting one or the other of a variety of such transfer media, and then employing the panels of such a medium, and portions thereof, in any desired order. The summary which follows describes further advantages exhibited by the invention in its several aspects.